Make sure you created a "management user" and "application user" using the "add-user.bat" file in the "<jboss-eap-install>/bin" directory, and use those users in Designer. Use the management user for "admin" connection, and application user for "Teiid" connection.

In the Designer, double click on the server profile you created, that will open a server configuration panel, on that click "Runtime Environment" link and edit the configuration file to "standalone-teiid.xml" then save and start the server.